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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/drivers/video/dummycon.c -- A dummy console driver
*
* To be used if there's no other console driver (e.g. for plain VGA text)
* available, usually until fbcon takes console over.
*/
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/screen_info.h>
#include <linux/init.h>
#include <linux/module.h>
/*
* Dummy console driver
*/
#if defined(__arm__)
#define DUMMY_COLUMNS screen_info.orig_video_cols
#define DUMMY_ROWS screen_info.orig_video_lines
#else
/* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */
#define DUMMY_COLUMNS CONFIG_DUMMY_CONSOLE_COLUMNS
#define DUMMY_ROWS CONFIG_DUMMY_CONSOLE_ROWS
#endif
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
/* These are both protected by the console_lock */
static RAW_NOTIFIER_HEAD(dummycon_output_nh);
static bool dummycon_putc_called;
void dummycon_register_output_notifier(struct notifier_block *nb)
{
WARN_CONSOLE_UNLOCKED();
raw_notifier_chain_register(&dummycon_output_nh, nb);
if (dummycon_putc_called)
nb->notifier_call(nb, 0, NULL);
}
void dummycon_unregister_output_notifier(struct notifier_block *nb)
{
WARN_CONSOLE_UNLOCKED();
raw_notifier_chain_unregister(&dummycon_output_nh, nb);
}
static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
{
WARN_CONSOLE_UNLOCKED();
dummycon_putc_called = true;
raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
}
static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
int count, int ypos, int xpos)
{
int i;
if (!dummycon_putc_called) {
/* Ignore erases */
for (i = 0 ; i < count; i++) {
if (s[i] != vc->vc_video_erase_char)
break;
}
if (i == count)
return;
dummycon_putc_called = true;
}
raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
}
static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
{
/* Redraw, so that we get putc(s) for output done while blanked */
return 1;
}
#else
static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
int count, int ypos, int xpos) { }
static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
{
return 0;
}
#endif
static const char *dummycon_startup(void)
{
return "dummy device";
}
static void dummycon_init(struct vc_data *vc, int init)
{
vc->vc_can_do_color = 1;
if (init) {
vc->vc_cols = DUMMY_COLUMNS;
vc->vc_rows = DUMMY_ROWS;
} else
vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
}
static void dummycon_deinit(struct vc_data *vc) { }
static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
int width) { }
static void dummycon_cursor(struct vc_data *vc, int mode) { }
static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
unsigned int bottom, enum con_scroll dir,
unsigned int lines)
{
return false;
}
static int dummycon_switch(struct vc_data *vc)
{
return 0;
}
static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
unsigned int flags)
{
return 0;
}
static int dummycon_font_default(struct vc_data *vc,
struct console_font *font, char *name)
{
return 0;
}
static int dummycon_font_copy(struct vc_data *vc, int con)
{
return 0;
}
/*
* The console `switch' structure for the dummy console
*
* Most of the operations are dummies.
*/
const struct consw dummy_con = {
.owner = THIS_MODULE,
.con_startup = dummycon_startup,
.con_init = dummycon_init,
.con_deinit = dummycon_deinit,
.con_clear = dummycon_clear,
.con_putc = dummycon_putc,
.con_putcs = dummycon_putcs,
.con_cursor = dummycon_cursor,
.con_scroll = dummycon_scroll,
.con_switch = dummycon_switch,
.con_blank = dummycon_blank,
.con_font_set = dummycon_font_set,
.con_font_default = dummycon_font_default,
.con_font_copy = dummycon_font_copy,
};
EXPORT_SYMBOL_GPL(dummy_con);
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